To simulate the pH of blood, which is 7.4, an undergraduate researcher in a biology lab produced a buffer solution by dissolving sodium dihydrogen phosphate (Ka = 6.2 × 10-8) and sodium hydrogen phosphate (Ka = 3.6 × 10-13) together in an aqueous solution. What mole ratio of Na2HPO4/NaH2PO4 did she need to use?